Structural and optical evolution in Pb100-xAgxSe (x = 3, 6, 9 and 12) thin films by chemical bath deposition

We developed a simple room-temperature synthetic route that achieves well-crystallized Pb100−xAgxSe alloy thin films by chemical bath deposition (CBD). The strategy provides a new paradigm to synthesize Ag doped PbSe thin films in one-step. We show that uniform distributed Pb100−xAgxSe thin films can be produced, whose crystal structure, morphology, and optical properties could be tailored with Ag concentration. With increasing x, both the shape and size of crystals are changing. Besides, the growth mechanism transits from cluster to ion by ion (IBI). The optical band gap (Eg) of the thin films is found to linearly increase with x values, from 0.26 eV to 0.31 eV. The density of states (DOS) and energy band structure of Pb100−xAgxSe are calculated using the first principle method. The calculation shows that Se 4p hybrids with Ag 4d at the valance band maximum, and the contribution to the conduction band minimum is mainly from Pb 6p and Ag 5s. The energy band gap shows the same tendency with Ag concentration as that in the experiment.